The invention relates to a method for smoothly connecting a load during an activated cylinder deactivation process of an internal combustion engine.
In the case of the operation of internal combustion engines, in particular gas engines, with a plurality of cylinders which are arranged in two cylinder banks, it is known to provide a cylinder deactivation process in the lower engine map range, in particular while idling, in order to save fuel and in order to optimize the power output. Said cylinder deactivation process also serves, in particular, to reduce pollutants. Cylinder deactivation processes of this type are usually performed in gasoline engines.
As a result of the deactivation of individual cylinders, the remaining cylinders have to produce the required power output of the internal combustion engine. This results in a higher specific cylinder power output of the active cylinders. In order to be able to produce a higher specific power output of this type in quantity-regulated engines, an increase in the boost pressure is required. This is usually realized by way of a change of the throttle valve position. If the deactivated cylinders are then activated again during the operation of the internal combustion engine, torque surges occur, that is to say brief increases in the respective torque, since the boost pressure of the internal combustion engine is still regulated to the operation with the reduced number of cylinders. The boost pressure is then reduced only during a subsequent setting of the required power output of the internal combustion engine.
A stepped individual activation of individual cylinders does not remedy the described problem, since torque surges nevertheless occur.
In gasoline engines, leaning of the mixture and an associated reduction in the fuel power output is not possible or is possible only within very small limits, since there is the risk of misfires. In the case of leaning of the mixture to values, at which it can still be burned reliably, the above-described torque surges nevertheless occur.
The torque surges are undesirable, in particular, because they involve loads on the drive train. Furthermore, the smooth running of the internal combustion engine is impaired, and there is the possibility of rotational speed fluctuations.